A flexible synthetic procedure to access a new and biologically interesting class of N,O-psiconucleosides by 1,3-dipolar cycloaddition of C-ethoxycarbonyl-N-methyl nitrone with ethyl 2-(acetyloxy)acrylate, followed by Vorbruggen nucleosidation and sodium borohydride reduction, is described. (C) 2001 Elsevier Science Ltd. All rights reserved.